Small boat oil removal system for bilge water

ABSTRACT

The water and oil that is normally collected in the bilge of small boats is pumped overboard by a bilge pump with the oil being removed from the bilge water by a filter having layers of different size expanded resin particles that are hydrophobic and oleophilic. When operation of the bilge pump ceases, a valve will release the back pressure that would otherwise be caused by the filter, to facilitate start-up of the pump. At the discharge and visible on the exterior of the boat, there is an indicator that will change color when it is in contact with oil, to provide a visual indication when the filter needs changing.

United States Patent [1 1 Pedone 1451 Oct. 21, 1975 1 1 SMALL BOAT OILREMOVAL SYSTEM FOR BILGE WATER it 21 Appl. No.: 492,168

52 U.S.Cl ..114/1s3 R;2l0/194;210/258;

. 210/290 511 int. cu ..B63B 29/16 [58] Field of Search..... 114/183 R,184, .5 R, 74 R, 114/74 A, .5 T, 125; 210/120, 121, 136, 73,

3,643,802 2/1972 Jackson, Jr. 210/460 3,820,658 6/1974 Cruze, Jr.210/290 3,841,484 10/1974 Domnick 210/95 3,852,193 12/1974 Jakubek et al210/73 Primary ExaminerTrygve M. Blix Assistant Examiner-Stuart M.Goldstein Attorney, Agent, or Firm-Thomas E. Beall, Jr.

[57] ABSTRACT The water and oil that is normally collected in the bilgeof small boats is pumped overboard by a bilge pump with the oil beingremoved from the bilge water by a filter having layers of different sizeexpanded resin particles that are hydrophobic and oleophilic. Whenoperation of the bilge pump ceases, a valve will release the backpressure that would otherwise be caused by the filter, to facilitatestart-up of the pump. At the discharge and visible on the exterior ofthe boat, there is an indicator that will change color when it is incontact with oil, to provide a visual indication when the filter needschanging.

18 Claims, 5 Drawing Figures FILTER U.S. Patent Oct. 21, 1975 3,913,513

7 I p FILTER INDICATOR 3 SMALL BOAT OIL REMOVAL SYSTEM FOR BILGE WATERBACKGROUND OF THE INVENTION In 1973, there were approximately 1,213,000small boats, which would have a length of less than 65 feet, in Canadaand the US. as determined by the US. Coast Guard and State MarineRegistries that have inboard engines. The present invention is designedto be used with these small boats having inboard engines, to remove theoil from the bilge water and other water that is discharged overboard bythe boats to prevent pollution of the environment.

The Federal Water Pollution Control Act (FWPCA) prohibits the dischargeof oil or hazardous substances into the waters of the United States.This prohibition is stated in terms: discharge includes spilling,leaking, pumping, pouring, or dumping; and oilmeans any kind of oil inany form, including fuel oil, gasoline, lubricating oil, and oil mixedwith water in a vessels bilge. The US. Coast Guard and EnvironmentalProtection Agency Standards states that oil has been discharged in aharmful quantity if it causes a visible shinning rainbow ordiscoloration of the surface of the water.

At the present time, boats with inboard engines commonly have bilgesthat collect water, fuel oil, gasoline, and lubricating oil. For safetypurposes, a bilge pump is operated to pump this mixture overboard priorto starting of the engine, and during operation of the engine, the bilgepump is periodically operated to further remove the combination of bilgewater and oil. Commonly, this will result in the discharge of a harmfulquantity of oil as determined by the above standards.

One way that has been suggested to meet the above standards is toprovide a holding tank within the boat, into which the bilge water andoil is pumped during op eration of the boat, so that upon docking, thebilge water with oil will be pumped to an on'shore system. For safetyreasons, the bilge water and oil must be removed from the enginecompartment in some manner during operation and during start-up of theengine to prevent explosions and fires.

Large oil, water separaters have been provided for large ships, but thesize and cost of these systems generally prohibit their use on smallrecreational boats and small commercial boats of the type describedabove. Further, such systems are mainly concerned with recovering bulkoil and not with removing small quantities of oil, so that they would nodoubt be incapable of meeting the above standards. Further, such systemscould not operate with a conventional small boat bilge pump, becausesuch pumps are extremely sensitive to back pressure and the pumps wouldfail to start-up, so that their associated motors would quickly burn outand a general failure of the system would result. Bilge pumps for smallboats are manufactured to pump a volume of liquid within the range of300 gallons per hour to 1,400 gallons per hour. Normally, there is onepump for each boat, depending upon the size of the boat and thecompartmentation of the bilge-ballast area. These bilge pumps arecommonly used with smallboats having inboard engines, which include thefollowing types: inboard, houseboat, inboard out drive,*yacht, and commercial.

SUMMARY OF THE INVENTION The present invention relates to a filteringsystem for removing small quantities of oil from water, particularly foruse with small boats, although according to the broader aspects of thepresent invention, it may be used for other installations, such asindustrial installations and swimming pool filter systems to remove bodyoils and sun tan lotion oils that would otherwise grow algae anddiscolor the water within the swimming pool.

The present invention is particularly suitable for use with small boatshaving inboard engines, wherein the conventional bilge pump is installedin series with a filter, a back pressure relief valve, and a visualindicator. After operation of the bilge pump, the back pressure that hasbeen created between the filter and the pump is relieved by the valve,so that upon start-up, the bilge pump will be able to start-up withoutany back pressure. The filter is provided with alternate layers of largeparticle expanded resin material and small particle expanded resinmaterial; it has been found that the use of only large particles willnot sufficiently remove the oil to satisfy the new standard fordischarge of oil into the waters of the United States, and it hasfurther been found that the use of only small particles that would meetthese standards, will quickly result in a failure of the filter by thewater forming channels through the small particles so that the waterwill bypass the material and discharge its oil directly overboard. Witha combination of large and small particles, it has been found that thelarge particles will permit the dispersion of the flow transverse to thegeneral flow direction for distributing the flow, while the layer ofsmall particles will satisfactorily remove the oil from the flowingwater and be of a length in the direction of flow short enough toprevent channeling. The synthetic resin material that is chosen for theparticles is preferably expanded polyurathane that will pick up between50 and times its weight in oil, without materially changing in size.With the material being tightly confined within a filter unit to preventchanneling, this ability to maintain its particle orientation and sizewhile picking up oil is extremely important.

For purposes of law enforcement and routine maintenance, a visualindicator is provided at the discharge end of the system, where theclean water is discharged overboard. Tlfe indicator will include amaterial that will pick up the oil and change in color, so that when thefilter fails upon being saturated with oil, the oil that is then passedthrough the filter will quickly discolor the indicator to show that thefilter should be replaced.

With the above-mention system, under actual test conditions, it is beenshown that the water discharged overboard leaves no visible sheen,rainbow, film or discoloration of the surface of the open water. Inaddition, the water pumped overboard meets the United States Coast Guardand Environmental Pollution Agency Standard in which the oil is removedto at least ten (10) parts per million.

BRIEF DESCRIPTION OF THE DRAWING Further objects, features andadvantages of the pres ent invention will become more clear from thefollowing detailed description of a preferred embodiment, as shown inthe accompaning drawing, wherein:

FIG. 1 is a cross-sectional, somewhat schematic, view of a small boatemploying the features of the present invention; 7

FIG. 2 is a longitudinal cross section through a disposable filter ofthe present invention;

FIG. 3 is a longitudinal cross sectional view taken through a permanentfilter housing containing therein a disposable filter cartidge, thatwould be used in place of the filter as shown in FIG. 2 for thecombination of FIG. 1;

FIG. 4 is a cross sectional view taken through the visual indicator thatis schematically shown in FIG. 1; and

FIG. is a cross sectional view taken through the relief valve that isschematically shown in FIG. 1.

The preferred embodiment of the present invention is designed to be usedin combination with small boats with inboard engines, with small boatsbeing defined as commercial and recreational boats having a lengthgenerally less than 65 feet, which boats have problems peculiar to theirsize. According to the broader aspects of the present invention, thefluid system may be used with a standard filtration system for aswimming pool to remove the oils normally found in swimming pool waterfrom sources such as sun tan lotion, and normal body oils, which oilstend to promote thegrowth of algae that will discolor the water andrequire higher concentrations of chlorine or similar material.

Withrespect to the preferred embodiment as shown in FIG. 1, only aportion of a small boat is shown, because the boat may be of any smallboat design and the actual design of the small boat forms no part of thepresent invention. The small boat includes a hull 1 that extendspartially above the normal water line 2 and partially below the normalline. For propulsion of the boat, there is a driven propeller 3 belowthe water line, which is drivingly connected to a drive shaft 4 thatpasses through the hull l and is connected at its inboard end to aninboard engine 5. The engine 5 is mounted within an engine compartment6, which in the particular example of a boat design is formed by thehull l anda partition 7. In a conventional manner, bilge water and oilfrom the engine is collected in the bottom of the engine compartment 6,which oil may be obtained from bearing grease, engine lubricating oilleakage, gasoline leakage, and the like. In a conventional small boat,the bilge water and oil is pump overboard by a bilge pump prior tostarting the engine, to remove the-hazards of an explosion or firecaused by igniting of the oil that is mixed with the bilge water, andfurther the bilge pump is conventionally operated whenever needed toremove bilge water and oil during operation of the engine.

According to the present invention, the bilge pump 8 has an inletconnected to an inlet pipe 9 that extends from the bilge pump 8 toclosely adjacent the lower most portion of the engine compartment, sothat the bilge pump 8 may suck bilge water and oil into the pump anddischarge the smae at a higher pressure through a pump outlet 10. Thepump outlet 10 is fluid connected to a pressure relief valve 11, whichis more fully shown in FIG. 5, which will maintain the pressure of thebilge water and oil passing through the bilge pump outlet 10 withoutdischarging the bilge water and oil into the engine compartment duringnormal operation of the pump, and further which will permit relief ofthis pressure at the pump outlet 10 when the pump is shut down. Therelief valve 11 is so constructed that it will vent the pump outlet 10to the atmosphere within the engine compartment after the pump has beenshut down and during start-up of the pump, that is, the relief valve 11will not close until after normal pressure has been obtained at the pumpoutlet 10 as a result of normal pump operation or rated speed of themotor (not shown) drivingly connected to the pump.

After leaving the vicinity of the back pressure relief valve 11, thepumped high pressure bilge water and oil travels to thefilter 12 thatmay be of the type shown in FIG. 2 or shown in FIG. 3, where the bilgewater and oil entering the inlet 13 will be filtered so that only bilgewater will leave under pressure through the filter outlet 14 until suchtime as the filter 12 becomes saturated with oil. The thus filteredbilge water, which is now clear of oil, will enter the inlet 16 of anindicator 15, to leave the indicator at 17 for discharge through theoutboard nozzle 18. The indicator 15, which is more fully shown in FIG.4,'includes a material that will discolor or change in color when it isin contact with small quantities of oil, which color will be visiblefrom the exterior of the boat to give an indication that oil is passingthrough the filter, which occurs as a result of saturation of thefilter. With the present invention under actual tests, a normal filtershould last I boating season, and if the boat is used yearround, twofilters may be required. The indicator will provide an indication to theboat owner or operater that the filter needs changing, and it will alsoprovide an indication to law enforcement agencies that the boat isdischarging a significant amount of oil overboard, even though the bilgepump may not be working at the time the inspection is made.

A disposable filter 12 is shown in more detail in FIG. 2, wherein thereis provided a one piece housing 19 that is preferably molded from asynthetic resin so as v to provide at one end a nipple that may be usedas either the inlet 13 or the outlet 14 of the filter unit, which may inturn be provided with internal or external threads, or external ridgesto engage a hose clamped about the nipple, which securement features arenot shown since they may be of any conventional type. The other end ofthe housing 19 is closed by means of an end plate 20 that may be heatsealed or otherwise bonded to provide a fluid tight connection with thehousing 19. The end plate 20 further has an integral nipple that mayprovide the inlet connection 13 or the outlet connection 14, in acorresponding manner. Preferably, the end plate 20 is molded in onepiece from a synthetic resin or metal. The material that fills theinteriorof the chamber formed by the housing 19 and end plate 20 is of aconstruction that is symetrical with respect to the opposed ends, sothat the filter is reversible in installation to simplify installationand to simplify construction. Immediately adjacent each end, there is alayer of a sheet of synthetic resin foam that will freely pass both oiland water, preferably without absorption of the oil to any materialextent. Immediately adjacent and to the interior of the sheet foam layer2l, there is a deflector or baffle plate 22, that is preferably formedby a solid sheet of synthetic resin having a plurality of axiallyextending holes or perforations, which plate in combination with thesheet foam will provide for even distribution of the liquid across theentire extent of the sheet, that is, the liquid entering the inlet 13will be dis persed radially outward for even distribution across theentire cross-section of the housing 19. Again, the oil and water willpass through the plate 22, without any significant retention. The fluidwill then pass through alternate layers of large particle expandedsynthetic resin 23 and small particle expanded synthetic resin 24.

After passing through these alternate layers 23, 24, where the oil isremoved from the bilge water, the filtered water will pass through theopposite end deflector plate 22, which will now function mainly to holdback the bulk of the large particles within the layer 24. Thereafter,the filtered water will pass through the sheet foam layer 21, which willserve to permit relatively free radial travel of the filtered waterinwardly towards the outlet 14 and further prevent passage of any smallparticles of the expanded resin.

The particular oil absorbent filter material has an extremely highabsorption capability with respect to oil and can absorb approximately50 to 70 times its own weight in oil. The material is also non-leachingso that regardless of thepassage of time, the oil will not return to thewater after it has been absorbed by the resin. Also, the material doesnot significantly change in size or composition when mixed with oil evento the point of saturation, and this material is non-toxic so that noadverse chemicals are added to the water that is discharged from theboat. While being oleophilic, the material is hydrophobic due to thedifference in surface tension between oil and water with respect to thepores of the expanded resin.

As one method of constructing the filter material, polyurethane isexpanded to form a rigid foam according to a conventional process, andthereafter a Pullman type of cutting mill, which is a knife millemploying three sharp rotating blades, is used to chop the rigidpolyurethane foam in small granules or particles, which are thereafterpassed through screens to obtain the large particles for the layer 23and the small particles for the layer 24. The actual cutting of therigid foam has been found to be critical with respect to obtainingmaximum oil absorption, which is as high as 50 to 70 times the weight ofthe resin. This has been found to be true because a grinding or crushingto obtain the particles will result in closed cell particles, becausegrinding will produce sufficient heat to heat seal or self-skin thecells, even though the cells are reduced in size, and crushingwill'merely reduce the size of closed cells without opening them up. Incontrast, cutting of a closed cell will open up one wall of the cell forfree access of oil to the interior of the cell, and greatly increase thesurface area of the resin exposed to the oil. In fact, the method offorming the particles, for maximum oil absorption, is so critical thateven dull blades of a Pullman type cutter mill will generate sufficientheat to close off the cells and significantly reduce the oil absorptioncapacity of the particles. It has been found that the preferred range ofparticle size is from 1,600 microns to about 10,000 microns. It has beenfound that when an expanded rigid synthetic resin has been processedaccording to the present invention through a Pullman cutter mill withsharp blades, it will absorb approximately 400% more oil than whenprocessed through a grinder to produce the same sized particles. Aphysical examination of the cross section of cut material according tothe present invention will show that the cut face exposes an undistortedcell interior. The resulting particles have a density of approximately 3pounds per cubic foot.

The particles that have been obtained by the foregoing method are passedthrough selected screens to first provide fine or small sized particlesof 2,000 microns or smaller, and thereafter produce large size particlesfalling within the range of 5,000 microns to 2,000 microns.

In actual experiments, it has been found that if only the larger sizedparticles where used, the oil and water would have a satisfactorydistribution throughout the interior of the filter, but small quantitiesof oil would pass through the filter long before saturation is reached,so that discharge of the filtered water would produce a visiblesheen onthe surface of open water and not meet the standards discussed above.Further, actual experiments have shown that if the smaller particlematerial was used (that is having a size of 2,000 microns or less) allof the oil would be satisfactorily removed from the water initially, butvery quickly the water passing through the filter would form channelsthrough the smaller particles so that there would be very little contactbetween the particles and oil resulting in passage of 'oil through thefilter to produce a visible sheen upon the open water where the filteredwater is discharged long before the filter became saturated; in fact,with the smaller particles, the walls of the formed channels wouldabsorb oil but the interior particles removed from the channels wouldnot be in contact with the moving oil and water, so that absorptionwould be greatly hindered. The water and oil passing through a filterwith smaller particles will almost immediately form channels to resultin failure of such a filter. According to the present invention, it hasbeen found that alternating layers of large particle filter material(particles falling within the range of approximately 2,000 to 5,000microns) with layers of small particles of filter material (particleshaving a size of 2,000 microns or less) will evenly distribute the flowof liquid throughout the filter so that uniform saturation of the filtermaterial will: proceed from the inlet to the outlet to provide formaximum oil absorption and saturation of the filter before the filterwill fail and pass oil, and further the smaller particles willsatisfactorily remove the oil to meet the afore mentioned requirementsand standards. It has been found in actual tests, that the filter willoperate until substantially all of the filter material is saturated withoil, without forming any channels even in the layers of smaller particlematerials, when the smaller and large particle layers are alternated asshown. Preferably, it has been found most desirable to provide the smallparticle layers with a length, in the general direction of fluid flow,that is between 2 and 4 times as long as the length of the largeparticle layer, and most preferably 3 times as long. It is felt that thefunction of these layers is as follows: the large particles will, inaddition to absorbing oil, evenly distribute the liquid flow throughoutthe transverse cross section of the filter to prevent subsequentchanneling in the small particle layers, and the small particles willall be in contact with the moving liquid due to such distribution, andfurther will be very efficient in removing the oil from the liquid dueto their small particle size so that no oil will be passed beyond thestandards mentioned above until saturation is reached. The number ofalternating layers will generally determine the life of the filter, andit has been found that filters approximately 4 inches in diameter andapproximately 12 inches in length with alternating layers of 1 inchlength large particles and 3 inch length small particles will serve toremove oil from the bilge water and satisfy the above mentionedstandards throughout operation for a normal boating season, withoutsaturation of the filter. Although in FIG. 2 the relative size of thealternating layers has not been indicated as falling within the aboverange, the above mentioned ranges are preferable. p

The deflector plate 22 and sheet foam distribution layer 21 are notessential to the present invention, but they do provide furtheradvantages. Particularly, the deflector plate will initially evenlydistribute the liquid across the transverse crosssection at the interiorto provide an even distribution of the pressure of the liquid at theentrance, and the plate at the opposite end will assure maintenence ofthis distribution. Further, the sheet foam layer 21 will provide aspacing or manifold cavity for the deflector plate and in addition willprevent smaller particles of the filter material from traveling throughthe filter outlet 14. It is thus seen that each of the elements 21 and22 provide a function at either the inlet or the outlet, which furtherfacilitates the reversibility of the filter.

The alternating layers of different size particles further has an effectin reducing the back pressure on the bilge pump, and it has been foundthat with respect to conventional bilge pumps, the back pressure is acritical factor in bilge pump failure. The physical size of the filterwill also depend upon the capacity of the bilge pump, and bilge pumpswithin the small boat field generally fall within the range of 300gallons per hour to 1,400 gallons per hour.

Since the particles are preferably cut as described above, the largeparticle layer is a mass of particles with cutand rough side so thatwhen the liquid hits the layer upon start-up, it will cause theirregular surfaces to lock together while diffusing the force of thefluid stream throughout the full area of the filter. The action of thecourse particles is very much like the action of trap rock used in roadconstruction. As in a french drain, the trap rock is compacted intoplace thus providing a solid base for a roadbed while permitting thefree passage of water; the filtered alternating layer constructionoperates in much the same way with the larger particles forming a firmbase for the smaller particle layer and distributing the flow evenly tothe smaller particle layer. Thus, channeling and wash out is preventedin the smaller particle layer.

It has been found that the filter with these alternating layers willoperate until saturation without forming channels, and without thesmaller particles migrating into the larger particles, both of whichfaults would occur if the filter were made up of only smaller particles.Upon start-up of the bilge pump, the fluid force will hit the filter bedand compress the filter material much in the manner of a coil spring,but the entire mass will be compacted and moved in the direction offluid flow a small amount wihtout disturbing the orientation or layeringof the particles. When the fluid pressure is relieved by stopping thebilge pump, the mass of material will expand back generally into theoriginal position thus freeing restrictions due to localized conditionsand further to prevent the tendency to form channels.

Actual tests have shown that if the large particle material having asize between 2,000 and 5,000 microns is provided throughout the entirefilter, no matter how tightly it is packed, it will allow oil topassentirely through the filter because of the large percentage of voidsbetween the particles without sufficiently contacting the absorbentmaterial with the oil, so that contaminated liquid will be dischargedfrom the filter in violation of the preceeding standards, starting verysoon after the installation of a new filter, and long before sat urationis'reached. Of course, this problem would be even greater with largersized particles.

On the other hand, if only the finer sized particles were used (having asize of 2,000 microns or less) throughout the entire filter, thefollowing problems would occur: if the absorbent material were veryfirmly packed in an effort prevent channeling, the restriction to theflow of fluid through the filter would be so great that the resultingback pressure would cause bilge pump failure very quickly. If theabsorbent material of the smaller sized particles were lightly packedthroughout the entire extent of the filter to reduce the back pressureto an acceptable level, channeling would occur where the liquidtraveling through the filter would form easily recognized visiblechannels through the filter so that there would be insufficient contactbetween the oil and filter material so that very quickly the filterwould pass contaminated liquid in violation of the above standards.

In FIG. 3, there is shown a permanent installation for the filter, whichstructure may be used in place of the structure shown in FIG. 2, so thateither the filter of FIG. 2 or FIG. 3'may be used in the system ofFIG. 1. In FIG. 3, a disposable cartridge 25 may be used that isidentical to all of the structures shown in FIG. 2, except that it mayor may not include the nipples described with respect to FIG. 2. Thuswith respect to the disposable cartridge 25, identical numerals havebeen provided for structure that is identical to that described withrespect to FIG. 2, and further description therefore of these elementswill be unnecessary.

The disposable cartridge 25 of FIG. 3 is preferably contained within apermanent cup-shaped member 26 that may be constructed of metal. A coilspring 27 is provided between the lower end of the cartridge 25 andcup-shaped housing 26, to provide a spacing between these two elementsand permit flow of fluid into or out of the opening 33 of the cartridge25. The other end of the cartridge 25 is held in place by means of a cap28 that is externally threaded and secured to the open end of thecup-shaped housing 26 by internal threads on the housing 26. The cap 28may be rigid plastic or metal, and is provided with a fluid passage 29that opens to the side to provide either the inlet 13 or the outlet 14of the filter and at its other end opens to the interior of the filterhousing in alignment with the opening 30 of the cartridge 25. TI-Ie cap28 is further provided with a fluid passage 31 that opens on theopposite side of the cap 28 to provide either the inlet or outlet and atits other end opens to the annular passage between the cartridge 25 andsubstantially larger housing 26. This thus formed annular passage andthe end space provided by the spring 27 form a chamber 32 to provideliquid commumication between the port 31 and the opening 33 exteriorlyof the cartridge 25. The cartidge 25 is held in this central location toassure the formation of the chamber 32, by means of a recess 34 in thelower end of the cap 28, into which the upper end of the cartridge 25 isresiliently held to form a seal between the cartridge 25 and the end cap28 while at the same time providing communication between the passage 29and opening 30. Thus, it is seen that if the passage 29 were used as theinlet, fluid would pass through the opening 30, through the interior ofthe cartridge 25, through the opening 33, through the spring 27, throughthe chamher 32 and through the passage 31. The outlet end of each of thepassages 29 and 31 is provided with either internal, as shown, orexternal, not shown, threads for securing pipes orthe like, or ridgesmay be provided for securing resilient hoses with hose clamps.

When it is desired to change the filter at the beginning of a season, orwhen saturation is reached as shown by the indicator 13, the housing 26is easily unscrewed from the cap 28, so that the cartridge 25 may bethrown away and replaced by a new cartridge 25 without disconnecting anyflow lines.

The visual indicator as shown in FIG. 4 may be of many different typesof construction, but is preferably formed by a one (1) piece moldedsynthetic resin generally cup-shaped member 43 having an inlet nipple16, and a generally cup-shaped one piece molded synthetic resin member44 that has an outer peripheral and redial flange 45, with an indicatormaterial 47 clamped therebetween around the joining periphery 46 of themembers 43 and 44. The member 44 is constructed of a transparentmaterial that will permit viewing of the indicator material of atransparent material that will permit viewing of the indicator material47 from the exterior (to the right of FIG. 4) of the boat hull l substantially above the water line as shown in FIG. 1. The periphery 46 may bebonded by any conventional manner to provide a fluid tight closure andto securely hold the material 47 around it periphery. The material 47may be a white cotton fabric that will quickly pickup and be discoloredor colored by any oil passing through the indicator to provide a visualindication through the clear member 44 to the exterior of the boat hull1 that the filter 12 is passing oil.

The relief valve of FIG. 5 has been found to be extremely important withrespect to preventing early bilge pump failure. While the relief valvemay take on many forms and may be chosen from a standard line ofsimilarly operated valves, the preferred form of the valve is shown inFIG 5, wherein a one piece synthetic resin member is molded with opposedconnectors 35' and 36, which may have means on them for securing thefluid lines, for example, external ridges to engage resilient tubes thatare provided with hose clamps. An upstanding annular wall 37 forms avalve chamber having at one end the opening 38 formed by a peripheralshoulder that supports a perforated retention plate 39, which plate inturn supports a float valve 40 that may be a standard ping pong ball.The upper end of the valve chamber is closed by means of a cap 41, whichmay be constructed in one piece of a synthetic resin and bonded to theannular member 37. The cap 41 is provided with a circular opening 42that may be formed with any type of sealing lip to cooperate with thefloat valve 40. In operation, the connectors 35 and 36 may function aseither the inlet or outlet, so that when installed in the system of FIG.1, the valve 11 will function to eliminate any back pressure on thebilge pump 8 during start-up, because initially the bilge pump 8 willbe'purging itself and the connecting lines of air, which air will freelypass through the valve 11 without passing through the considerablerestriction of the filter 12 so that the pump 8 may start-up and reachits rated speed and start pumping liquid before there is any backpressure produced on the pump. Once liquid is pumped to the valve 1 1,the liquid will enter thetvalve chamber and force the float valve member.40 upwardly to seal the opening 42, so thatthereafter all of the liquidpumped by the pump 8 must pass serially through the filter l2, indicatorl5, and outlet 18 to be discharged to the open water surrounding theboat. Upon shutdown, leakage will occur and the back pressure will berelieved through the valve 11, filter 12, and the pump 8, so that againupon start-up there will be no back pressure on the pump 8. In actualtests, it has been found that the commercially available bilge pumps areextremely sensitive to back pressure, and that the back pressure onthese pumps is critical with respect to their early failure.

While the layering construction of the filter is quite important withrespect to relieving back pressure, it has been found that the reliefvalve is even more important with respect to eliminating back pressureduring startup. In actual tests without the valve 11, it was found thatthe filter and any trapped liquid would many times provide sufficientback pressure to the pump 8 so that the pump would not start-up and themotor operating the pump would quickly burn out. It is known that motorsdraw the most current when they are starting-up and that pumps requireconsiderable power during start-up due to the inertia of their moveableparts, so that if back pressure were added to the pump, the total resultis many times enough to prevent start-up of the pump and burn out themotor.

Since operation of the individual parts has been described along withtheir construction, a separate operation will not be set forth indetail.

While the preferred embodiment relates to the system for removing bilgewater from a boat and preventing the discharge of oil to meet the abovementioned standards, the illustrated system 9-18 may also be providedfor other installations, for example within a swimming pool filtrationsystem to remove suntan lotion oil and body oils from the water. Ifthese oils were not removed, they tend to support the growth of algaethat will greatly discolor the water and require the addition of largequantities of chlorine and other substances that are generallyundesirable. Further, the system could be used in industrialapplications, for example where cooling water may pick up lubricatingoil from machinery. These further uses are according to the broaderaspects of the present invention.

Further, the system can be expanded to a size large enough to service amarina and by having the boats by pass their filters and pump directlyinto a header system and then into a large dock side filter, anddischarge the clean water back into the main body of water.

While a preferred embodiment of the present invention has been shown anddescribed in detail for purposes of illustration and for the advantagesof the specific details, further embodiments, modifications andvariations are contemplated within the spirit and scope of the presentinvention, all as defined by the following claims:

1. In combination with a small boat having an inboard engine driving anoutboard propeller, with the engine being contained within a compartmentcollecting bilge water and oil from the engine, the improvementcomprising: serially fluid connecting inlet means adjacent the lowerportion of said compartment for collecting bilge water and carried oil,pump means connected to said inlet means for sucking bilge water and oilthrough said inlet means and discharging it at a higher pressure; filtermeans fluid connected to said pump means for receiving the pressurizedbilge water .and oil, and further for normally removing the oil from thebilge water and discharging only bilge water; and discharge means fluidconnected to said filter means for recieving the filtered bilge waterand discharging the filtered bilge water outside of said enginecompartment to the environment surrounding the small boat; said filtermeans including a housing having an inlet and an outlet for fluid, fluiddistribution means within said housing for directing the fluid along apredetermined path between said inlet and said outlet, a first mass ofparticles within said housing and in said path having a size within apredetermined range and being of an expanded open pore oleophilic andhydrophobic synthetic resin, and a second mass of particles within saidhousing and in said path spaced in the direction of fluid flow from saidfirst mass of a size within a range substantially less than the range ofsaid first mass of particles and being of expanded open pore oleophilicand hydrophobic synthetic resin; said smaller sized second mass ofparticles being interposed within said path between said larger sizedparticles and said outlet, so that said larger sized first mass ofparticles will constitute means to distribute the fluid transversely ofthe path for even distribution and said smaller sized second mass ofparticles will constitute means to efficiently remove the oil from thebilge water while passing the bilge water; and porous means interposedin said fluid path between said smaller sized second mass of particlesand said discharge means with a plurality of through passages smallerthan said smaller sized particle range of said second mass for passingthe filtered bilge water and blocking the passage of said smaller sizedparticles.

2. The combination of claim 1, further including visual indicator meansreceiving the filtered bilge water between said filter means and saiddischarge means for changing color in response to receiving any oil fromsaid filter to indicate the saturation of said filter, and saidindicator means being mountable on the small boat so as to be visiblefrom ouside of the boat.

3. The combination of claim 2 wherein said visual indicator meansincludes synthetic resin housing mounted within the boat hull above thenormal water line and having an inlet to the interior of the hull and anoutlet exteriorly of the hull; said indicator means further includingporous means within said housing and fluid interposed between said inletand outlet for absorbing any oil passing through said indicator means;and said indicator means housing further being transparent at least tothe extent to provide unobstructed vision through said housing from theexterior of said boat to said material means.

4. The combination of claim 1, wherein the particles of each of saidfirst and second mass contain cut and uncut expanded resin cells, withthe uncut cells being generally spherical and the cut cells beinggenerally truncated spheres with undistorted open ends.

5. The combination of claim 1, wherein said filter means has substantialsymmetry between said inlet and outlet for purposes ofinterchangeability and a serial arrangement along the path of fluid flowof distribution means, particle containing means, a mass of said largersized particles, a mass of said smaller sized particles, a mass of saidlarger sized particles, a second one of said particles containing means,and a second one of said distribution means.

6. The combination of claim 1, wherein said smaller sized particle firstmass has a length, as measured in the direction of said fluid path, thatis between two and four times as large as the corresponding length ofsaid larger sized second mass of particles.

7. The combination of claim 1, wherein there are a plurality ofimmediately adjacent alternating layers of said larger sized first massof particles and said smaller sized second mass of particles along andwithin said fluid path.

8. The combination of claim 1, further including re lief valve meansfluid connected between said pump means and said filter means to receivethe pressurized bilge water and oil for maintaining the pressure duringoperation of said pump means and venting said pump means discharged tothe atmosphere upon shut down and start-up of said pump means.

9. The combination of claim 8, wherein said filter means has substantialsymmetry between said inlet and outlet for purposes ofinterchangeability and a serial arrangement along the path offluid flowof distribution means, particle containing means, a mass of said largersized particles, a mass of said smaller sized particles, a mass of saidlarger sized particles, a second one of said particles containing means,and a second one of said distribution means.

10. The combination of claim 8, wherein said smaller sized particlefirst mass has a length, as measured in the direction of said fluidpath, that is between two and four times as large as the correspondinglength of said larger sized second mass of particles.

11. The combination of claim 8, wherein there are a plurality ofimmediately adjacent alternating layers of said larger sized first massof particles and said smaller sized second mass of particles along andwithin said fluid path. l

12. The combination of claim 1 1, wherein said smaller sized particlefirst mass has a length, as measured in the direction of said fluidpath, that is between two and four times as large as the correspondinglength of said larger sized second mass of particles.

13. The combination of claim 8, wherein said relief valve means includesa float type check valve means that will generally remain open for thepassage of air in either direction, and will close upon receivingpressurized liquid from said pump means.

14. In combination with a small boat having an inboard engine driving anoutboard propeller, with the engine being contained within a compartmentcollecting bilge water and oil from the engine, and bilge pump meanshaving an inlet adjacent the lower portion of said compartment forsucking bilge water and oil through the inlet and discharging it at ahigher pressure through a discharge outside of said engine compartmentto the environment surrounding the small boat, the improvementcomprising: filter means fluid connected between said bilge pump meansand said discharge for receiving the pressurized bilge water and oil,and further for normally removing the oil from the bilge water todischarge only clean water to the envi ronment; and relief valve meansfluid connected between said bilge pump means and said filter means forpassing all of the bilge water and oil from said bilge pump means tosaid filter means during normal operation without substantial pressureloss, and for admitting atmospheric air to the fluid connection betweensaid filter means and said bilge pump means when ever the pressure issubstantially below the normal operating pressure of said bilge pumpmeans, so that upon starting of said bilge pump means, said bilge pumpmeans may start-up and generally reach normal operation without backpressure produced by said filter means and anyother back pressureproducing means downstream from said relief valve means.

15. The combination of claim 14, wherein said relief valve meansincludes a float type check valve means that will generally remain openfor the passage of air in either direction, and will close uponreceiving pressurized liquid from said pump means.

16. The combination of claim 1, further including means for fluidbypassing said filter means to permit pumping and discharge of saidbilge water and oil outside of said engine compartment. by said bilgepump means without passing through said filter means.

17. The combination of claim 14, further including means for fluidbypassing said filter means to permit pumping and discharge of saidbilge water and oil outside of said engine compartment by said bilgepump means without passing through said filter means.

18. In combination with a small' boat having an inboard engine drivingan outboard propeller, with the engine being contained within acompartment collecting bilge water and oil from the engine, theimprovement comprising: serially fluid connected inlet means adjacentthe lower portion of said compartment for collecting bilge water andcarried oil, pump means connected to said inlet means for sucking bilgewaater and oil through said inlet means and discharging it at a higherpressure; filter means fluid connected to said pump means for receivingthe pressurized bilge water and oil, and further for normally removingthe oil from the bilge water and discharging only the bilge water;discharge means fluid connected to said filter means for receiving thefiltered bilge water and discharging the filtered bilge water ouside ofsaid engine compartment to the environment surrounding the small boat;visual indicator means receiving the filtered bilge water between saidfilter means and said discharge means for changing color in response toreceiving any oil from said filter to indicate the saturation of saidfilter; said visual indicator means including a synthetic resin housingmounted within the boat hull above the normal water line and having aninlet to the interior of the hull and an outlet exteriorly of the hull;said indicator means further including porous means secured to saidhousing and fluid interposed between said inlet and outlet for absorbingany oil passing through said indicator means; and said indicator meanshousing further providing unobstructed vision from the exterior of saidboat to said porous means for visual determination of the color change.

2. The combination of claim 1, further including visual indicator meansreceiving the filtered bilge water between said filter means and saiddischarge means for changing color in response to receiving any oil fromsaid filter to indicate the saturation of said filter, and saidindicator means being mountable on the small boat so as to be visiblefrom ouside of the boat.
 3. The combination of claim 2 wherein saidvisual indicator means includes synthetic resin housing mounted withinthe boat hull above the normal water line and having an inlet to theinterior of the hull and an outlet exteriorly of the hull; saidindicator means further including porous means within said housing andfluid interposed between said inlet and outlet for absorbing any oilpassing through said indicator means; and said indicator means housingfurther being transparent at least to the extent to provide unobstructedvision through said housing from the exterior of said boat to saidmaterial means.
 4. The combination of claim 1, wherein the particles ofeach of said first and second mass contain cut and uncut expanded resincells, with the uncut cells being generally spherical and the cut cellsbeing generally truncated spheres with undistorted open ends.
 5. ThecoMbination of claim 1, wherein said filter means has substantialsymmetry between said inlet and outlet for purposes ofinterchangeability and a serial arrangement along the path of fluid flowof distribution means, particle containing means, a mass of said largersized particles, a mass of said smaller sized particles, a mass of saidlarger sized particles, a second one of said particles containing means,and a second one of said distribution means.
 6. The combination of claim1, wherein said smaller sized particle first mass has a length, asmeasured in the direction of said fluid path, that is between two andfour times as large as the corresponding length of said larger sizedsecond mass of particles.
 7. The combination of claim 1, wherein thereare a plurality of immediately adjacent alternating layers of saidlarger sized first mass of particles and said smaller sized second massof particles along and within said fluid path.
 8. The combination ofclaim 1, further including relief valve means fluid connected betweensaid pump means and said filter means to receive the pressurized bilgewater and oil for maintaining the pressure during operation of said pumpmeans and venting said pump means discharged to the atmosphere upon shutdown and start-up of said pump means.
 9. The combination of claim 8,wherein said filter means has substantial symmetry between said inletand outlet for purposes of interchangeability and a serial arrangementalong the path of fluid flow of distribution means, particle containingmeans, a mass of said larger sized particles, a mass of said smallersized particles, a mass of said larger sized particles, a second one ofsaid particles containing means, and a second one of said distributionmeans.
 10. The combination of claim 8, wherein said smaller sizedparticle first mass has a length, as measured in the direction of saidfluid path, that is between two and four times as large as thecorresponding length of said larger sized second mass of particles. 11.The combination of claim 8, wherein there are a plurality of immediatelyadjacent alternating layers of said larger sized first mass of particlesand said smaller sized second mass of particles along and within saidfluid path.
 12. The combination of claim 11, wherein said smaller sizedparticle first mass has a length, as measured in the direction of saidfluid path, that is between two and four times as large as thecorresponding length of said larger sized second mass of particles. 13.The combination of claim 8, wherein said relief valve means includes afloat type check valve means that will generally remain open for thepassage of air in either direction, and will close upon receivingpressurized liquid from said pump means.
 14. In combination with a smallboat having an inboard engine driving an outboard propeller, with theengine being contained within a compartment collecting bilge water andoil from the engine, and bilge pump means having an inlet adjacent thelower portion of said compartment for sucking bilge water and oilthrough the inlet and discharging it at a higher pressure through adischarge outside of said engine compartment to the environmentsurrounding the small boat, the improvement comprising: filter meansfluid connected between said bilge pump means and said discharge forreceiving the pressurized bilge water and oil, and further for normallyremoving the oil from the bilge water to discharge only clean water tothe environment; and relief valve means fluid connected between saidbilge pump means and said filter means for passing all of the bilgewater and oil from said bilge pump means to said filter means duringnormal operation without substantial pressure loss, and for admittingatmospheric air to the fluid connection between said filter means andsaid bilge pump means when ever the pressure is substantially below thenormal operating pressure of said bilge pump means, so that uponstarting of said bilge pump means, said bilge pump means may start-upand generally reach normal operation without back pressure produced bysaid filter means and anyother back pressure producing means downstreamfrom said relief valve means.
 15. The combination of claim 14, whereinsaid relief valve means includes a float type check valve means thatwill generally remain open for the passage of air in either direction,and will close upon receiving pressurized liquid from said pump means.16. The combination of claim 1, further including means for fluidbypassing said filter means to permit pumping and discharge of saidbilge water and oil outside of said engine compartment by said bilgepump means without passing through said filter means.
 17. Thecombination of claim 14, further including means for fluid bypassingsaid filter means to permit pumping and discharge of said bilge waterand oil outside of said engine compartment by said bilge pump meanswithout passing through said filter means.
 18. In combination with asmall boat having an inboard engine driving an outboard propeller, withthe engine being contained within a compartment collecting bilge waterand oil from the engine, the improvement comprising: serially fluidconnected inlet means adjacent the lower portion of said compartment forcollecting bilge water and carried oil, pump means connected to saidinlet means for sucking bilge waater and oil through said inlet meansand discharging it at a higher pressure; filter means fluid connected tosaid pump means for receiving the pressurized bilge water and oil, andfurther for normally removing the oil from the bilge water anddischarging only the bilge water; discharge means fluid connected tosaid filter means for receiving the filtered bilge water and dischargingthe filtered bilge water ouside of said engine compartment to theenvironment surrounding the small boat; visual indicator means receivingthe filtered bilge water between said filter means and said dischargemeans for changing color in response to receiving any oil from saidfilter to indicate the saturation of said filter; said visual indicatormeans including a synthetic resin housing mounted within the boat hullabove the normal water line and having an inlet to the interior of thehull and an outlet exteriorly of the hull; said indicator means furtherincluding porous means secured to said housing and fluid interposedbetween said inlet and outlet for absorbing any oil passing through saidindicator means; and said indicator means housing further providingunobstructed vision from the exterior of said boat to said porous meansfor visual determination of the color change.